1. Field of the Invention
The present invention relates to an optical disk device and a control method thereof, and more particularly to an optical disk device permitting control for preventing collision between a disk and an objective lens and a control method thereof.
2. Description of the Background Art
Conventionally, in an optical disk device, reading of information recorded on a disk from light reflected from the disk via an objective lens has been performed. Some of such optical disk devices are provided with an actuator for displacement of the objective lens, where a signal to be applied to the actuator is controlled so as to control the position of the objective lens in the focus direction.
For position control of an objective lens in a focus direction for an optical pickup in an optical disk device, various techniques have conventionally been disclosed for preventing collision between the disk and the objective lens. For example, Japanese Patent Laying-Open No. 9-259444 discloses a technique to make an objective lens recede from a disk by means of a withdrawal mechanism thereof in accordance with a focus error signal that is generated based on a received-light signal of an optical pickup. Further, Japanese Patent Laying-Open No. 11-185363 discloses a technique to drive an objective lens in accordance with an impact applied to the optical disk device.
Conventionally, in the case where the position of the objective lens is controlled by a signal applied to an actuator, when a member holding the objective lens suffers an impact exceeding the range of normal displacement by the actuator, the member itself may oscillate, in which case subsequent position control of the objective lens by means of the actuator may be difficult. As such, there has been a demand for an optical disk device capable of preventing collision of the objective lens to the disk even in such a case.